Kentucky Fried Chicken, the largest chicken-on-the-bone quick service restaurant in the U.S., said Friday that by the end of 2018, all chicken purchased by KFC U.S. will be raised without antibiotics important to human medicine.

The move marks the first time a major national quick service restaurant chain in the U.S. has extended an antibiotics commitment beyond boneless chicken to its chicken-on-the-bone menu items, company officials said Friday.

Kevin Hochman, president and chief concept officer for Louisville, Ky.,-based KFC U.S., said making the change was complex and involved a lot of planning.

“It required close collaboration with more than 2,000 farms, most of them family-owned and managed, in more than a dozen U.S. states where they raise our chickens,” Hochman said.

McDonald’s Corp. stopped serving chicken raised with antibiotics important to human medicine last year. Wendy’s and Taco Bell have similar policies.

Chick-fil-A has pledged to sell only poultry raised without any antibiotics at all by the end of 2019.

Subway sells only products raised without any antibiotics at all, as do Panera Bread, Chipotle and Papa John’s.

KFC’s move was applauded by Consumers Union, the policy and mobilization division of Consumer Reports, the Natural Resources Defense Council, and others who started a campaign in 2015.

More than 80 public interest groups asked Yum! Brands, which includes KFC, to stop allowing routine antibiotics use among its meat and poultry suppliers. Medical experts say overusing antibiotics is threatening the public health by making these drugs less effective for treating disease in people.

Jean Halloran, Director of Food Policy Initiatives for Consumers Union. “Antibiotics should only be used to treat disease and not wasted on healthy livestock to make them grow faster or to compensate for filthy conditions on factory farms. It’s time for all fast food restaurants to help ensure antibiotics keep working by rejecting meat and poultry suppliers who misuse these vital drugs.”

Some 80 percent of all antibiotics sold in the U.S. are used not on sick humans but on healthy animals. These antibiotics are regularly fed to cows, pigs, and poultry to make them grow faster and to prevent disease in often crowded and unsanitary conditions on today’s industrial farms.

When antibiotics are used on the farm, the bugs that are vulnerable to them tend to be killed off, leaving behind “superbugs” that are resistant to antibiotics. Superbugs can spread from the farm to our communities via meat and poultry, farmworkers, and through the air, soil, and water. Antibiotic resistant infections pose a grave threat to public health because they are difficult to treat, resulting in longer stays in the hospital and too often death.

The Centers for Disease Control and Prevention estimates that at least 2 million Americans are infected with antibiotic-resistant infections every year , and that at least 23,000 die as a direct result.

KFC reports they will require their suppliers to work with the USDA Process Verified Program to ensure that production practices comply with the company’s commitments.